To the surprise of no one who saw the ratings and the social stats, NBC announced Monday that it’s turning last week’s live-musical/social media-palooza into an annual event. NBC Entertainment chairman Bob Greenblatt said today he’s already circling a couple of titles for next year but already has begun managing expectations, telling The New York Times, “There may be a little bit of a phenomenon to the first one of these. Who knows what happens Year 2, 3, or 4?”

NBC clocked an impressive 18.6 million viewers Thursday night with its three-hour broadcast of The Sound of Music, which became a social media phenom, with much of the attention paid by tweeters to star Carrie Underwood’s “thin acting resume” as the NYT put it. Underwood reacted to her professional and amateur critics by tweeting that “mean people need Jesus” and that she would pray for them.

That said, many of those critics cut her — and the broadcast, with its numerous technical glitches — a lot of slack, in an effort to show support for the idea of mounting live TV broadcasts, and family-friendly ones to boot. Here’s maybe the best example, from The Daily Beast (NYT thought so too): “It’s the least we can do to drop any cynicism over the project and harsh reaction to the execution of it and appreciate the huge gamble and undertaking it was to reanimate those mountains, and how fun it was to — even without Julie Andrews and even if it was kind of a mess — be twirling on them again.”

The show’s producers, Craig Zadan and Neil Meron, already have turned a slew of well-known musicals into TV productions – though not live ones. Back in December 1993, they made a lot of noise with their CBS broadcast of Gypsy, starring Bette Midler; it averaged more than 26 million viewers. They went on to redo The Music Man,Cinderella, and Annie for TV, though interest eventually died down. Not any musical will do for NBC’s new annual holiday franchise: Success, Greenblatt said, hinges on finding a title that can be rated G, as was The Sound of Music, and has loads of very familiar tunes – and on securing the services of another music star with a large fan base, like Underwood, hopefully one with a thicker acting resume, or thicker skin. Biggest news out of NBC’s announcement: Underwood spent 10 months preparing for the role.